In recent years, advances in multi-dimensional NMR spectroscopy have made possible the determination of the three-dimensional structures of proteins (of sizes less than 25 kD) and peptides in solution. In addition, side- chain and backbone dynamics measurements allow the determination of site- specific information on regions of flexibility. Internal motions of proteins, such as rotations of individual amino acid residues as well as concerted segmental motions of groups of residues, occur on widely different time scales and result from random thermal motions as well as interactions with specific ligands and or proteins. These fluctuations are recognized as being very important in biological functions, including enzyme catalysis, allosterism, protein-protein interactions and ligand binding. Current knowledge of the details of these motions is fragmentary. The Core Director has used these methods to study the folding and dynamics of sperm whale myoglobin. In addition, the Director has employed heteronuclear filtering methods to probe protein-ligand binding interactions. She will continue to use these methods to investigate the role of protein dynamics in protein systems of biological importance. We have assembled a core facility which will give access to this technology to all the Investigators of the Program Project. 1) to provide technical expertise in protein NMR measurements. 2) to provide aid in the design of new experiments to target specific questions of biological importance 3) to provide training to investigators in the use of NMR spectroscopy. The core facility is organized to offer maximum collaborative potential for all investigators, and to maximize the use of the latest state-of-the- art techniques to address problems of biological importance.